* {
    margin: 0;
    padding: 0;
}


/*去掉a标签的下划线*/

a {
    text-decoration: none;
}


/*去掉列表的样式*/

ul {
    list-style: none;
}


/*去掉input的默认样式，轮廓线和边框*/

input {
    outline: none;
    border: 0;
}


/*去掉按钮的边框*/

button {
    border: 0;
}


/*html默认字号*/

html {
    font-size: 16px;
    font-family: Tahoma, Arial, "Helvetica Neue", "Hiragino Sans GB", Simsun, sans-self;
}


/*专门定义居中区域*/

.center {
    width: 1000px;
    margin: 0 auto;
}


/*专门定义清除浮动的类名，供需要清除坍塌的父元素使用*/

.clearfix::after {
    content: "";
    display: block;
    clear: both;
}